I'm not sure about the Spotmatic F, so for simplicity, I'll skip it. With the lens off the camera, screw a rear cap on. That should press the tiny pin in. BTW, the tiny pin is a few degrees CCW of the square block on the mount, half-hidden here, not the larger chrome pin at the top:
Now slide the AUTO/MAN. switch so it says MAN. Set the aperture ring to f16 or so and the aperture blades should close. They should move whenever you change the aperture ring setting.
If you can't set the switch to MAN., it's that damned tiny pin. If you can get the switch to MAN. and still the blades don't move, the lens has to be disassembled for repair. The problem might be the blades or the aperture mechanism, both involving a lot of disassembly.